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What does pH stand for?

by: Charlene Rennick

Have you ever wondered why the “p” in “pH” is a lower-case letter while the “H” is capitalized? What does it mean?

The “p” stands for potential and the “H” stands for Hydrogen. Okay, so that makes it as clear as mud. What is potential Hydrogen? A scientific explanation would state that pH refers to the plant’s ability to attract hydrogen ions. A less scientific explanation says pH is the acid/alkaline balance.

Translated into a language those of us without the Ph D can understand, pH level refers to the amount of acid and alkaline contained inside of both the water and the growing medium or soil. If the environment is too acidic, that means the plant will not attract enough hydrogen, while an environment that is too alkaline will attract too much hydrogen. An environment that continually fluctuates from one extreme on the pH scale to the other is unhealthy for the plant.

Hydrogen is one of four elements any living plant needs to survive. Without hydrogen, the plant would wilt and not be able to take in nutrients. Because the plant contains hydrogen, it continues to absorb hydrogen through the water via a process called osmosis. This hydrogen-osmosis cycle is what keeps the nutrients traveling from the water into the plant. Once a plant has died due to lack of water, there is no amount of water that can be added to it that will cause the plant to be revived.

The level of pH is measured on a scale of 0 to 14 with 0 representing the highest concentration of acid and 14 representative of the most alkaline. Seven is the magic figure for pH because it means that there is a balance of acid and alkaline in the solution and is often referred to as pH neutral. It is usually sufficient to say that a pH neutral environment is perfect for most plants, but some vegetation requires water or a growing medium that is more acidic than alkaline in order to flourish or have the right colour of blossoms, while other plants prefer the opposite. Testing strips for pH can be purchased to determine exactly what the acid/alkaline balance is in your water, growing medium or soil. This makes it easy to adjust the level for home gardeners or for mixing nutrients for your own hydroponic garden .

Comments

Celia says

Victor says

Shane says

“The level of pH is measured on a scale of 0 to 14 with 0 representing the highest concentration of acid and 14 representative of the most alkaline.”

That is not true! pH values can actually range from lower than 0 to higher than 14. Take for instance 2 M HCl: the pH would be -log2 = -0.30. The 0 and 14 values are just given as endpoints because they represent the pH of 1 M H+ and 1 M OH-, respectively, which provides a good reference point.

Shane says

“Hydrogen is one of four elements any living plant needs to survive.”

This is not true either. There are many more elements that plants need to live, just like humans. Maybe they only need four elements in large concentrations, but other nutrients and minerals are needed as cofactors and coenzymes that are essential for enzymatic activity and plant functions. How about sodium and potassium? If you don’t have those, you can’t have action potentials!

Amy says

im doing a science fair project and it helped alot thanks. But i still dnt quite get why the p is in lowercase and the H is in captial can you clarify that a bit more?

Ross says

When I asked my chemistry teacher (who was head of the science faculty) what pH stood for he scratched his head thoughtfully for a few moments, then admitted that he didn’t know, and had never considered it before.

Herby Romulus says

lizzie says

Lily says

Sheina says

this sight is awesome.

thank you for everything. this website rocks and is perfect for my upcoming science fair project.

some of the commenters have given us their knowledge about pH also. thanks to bothe the site and commenters.

Sasha says

this is so cool.the info is straight forward and to the point. i appreciated this info alot thanks.

Grace says

Helped me to understand a lot, thanx. That Shane person is v. nerdy! For Amy, H is a capital because on the periodic table it’s like that. For lowercase p, it’s probably coz potential is not a proper noun so it wouldn’t usually have a capital anyway.